I am not an
official representative of Science Olympiad and rules clarifications need to
be addressed to the official Science Olympiad web-site.

The following is
a copy of the hand out I provided to students and coaches who attended my
Bottle Rocket Sessions at the Science Olympiad National Coaches Clinic held
in Hammond, Indiana (10-4-02).

1. Stiff fins
are the best fins. Flexibility decreases the effectiveness of a fin.

2. To trace the
bottle's shape on the fin material, place the bottle directly under a light
source.

3. Place the
grain of the fin perpendicular to the bottle. This will make the fin stiffer
and stronger.

4. Do not sand
the bottle prior to gluing. It will get you disqualified and is not
necessary.

5. Best glues
for fins: PL Premium - available at Home Depot or Lowes, Goop - available
at most hardware stores, Shoe Gu - available at shoe stores and sporting
good stores, 100% GE Silicone Glue - available everywhere. All hold well, PL
Premium is the stiffest, probably the most toxic, Shoe Gu and Goop are both
fairly stiff, GE Silicone is less toxic, but more flexible. Contact Cement
or Rubber Cement can be used to glue on paper fins. You should be in a
well-ventilated area and wear latex gloves when using PL Premium, Shoe Gu,
and Goop. It will usually take fins about 2 hours to cure enough to put on
another fin and about 2 days before launching.

6. "Swing
Testing" is a quick way to determine if a rocket has reasonable stability.
This test is done by tying a string around the rocket at its CG and swinging
the rocket around.

7. Fins cause
very little drag and do not weigh very much. A non-stable rocket that is
flying sideways is creating a lot of drag. Non stable rockets have a lot of
problems with pre-deployment of their parachute.

8. The cost of
non-vertical flight is tremendous. A flight that is 5 degrees off vertical
can loose 10% of its potential altitude.

9. Parachutes
are more efficient with more shroud lines. Shroud lines hold the shape of
the parachute and keep air from burping from the chute.

10. Parachutes
should be as large as possible while still meeting overall length
requirements and efficiency standards.

11. Parachute
efficiency is improved by using the correct shroud length. Shroud lengths
should be between 1.2 to 1.5 times the parachute diameter.

12. The best
parachute material that I have found is dry cleaner bags. If you request the
bags used by commercial cleaner for drapes or wedding dresses you may find
one large enough for your parachute.

13. The best
material for shroud line is nylon upholstery thread.

14. How much
water? 1/3 of the capacity of the bottle will get you close. Use simulator
listed on page 4.

15. When
humidity is low and there is no chance of rain, you can use talc to keep the
chute from having static cling.

16. The best
folding technique for passive deployment is to zig zag fold the cute,
starting from the top to bottom. When you fold the chute to the shroud
lines, gently make a couple of wraps with the lines. You want to use as few
wraps as possible so that the chute will deploy quickly.

17. The
parachute should be attached securely to the rocket. It can be glue or tied.
If glued, you should reinforce the bond with fiberglass reinforced packing
tape. This also applies to the cord that attaches the cone to the bottle.

18. Deployment
at apogee and a quick opening parachute are essential to increasing hang
time.

19. If the
rocket arches through apogee and does not slow down, wind drag will not
allow the cone and body to separate even with active deployment.

20. Make sure
that your cone sits securely on the rocket. I have seen numerous rockets
disqualified due to cones shifting during pressurization or by being blown
off by the wind.

21. The rules no
longer allow for a wind block to be used by a competitor to shield the
rocket from wind gusts during launch.

22. Beware,
bottles expand under pressure. The expansion can upset a cone if the rocket
is not designed to deal with this problem.

23. You can
design a cone that fits loosely on the bottle. It will need to be supported
by a ring or pegs. Both pegs and rings (butter tub seal) can be glued to the
rocket with PL Premium.

24. Many
competitors use poster board paper or banner paper to make their cone. See:
http://txsnapper.eezway.org/powerdeployment, for procedure to make a simple
cone.

25. If you use
pegs to sit the cone on, make sure to use Bass Wood (not balsa) and turn the
grain so that the G-forces of take off will not cause the cone to cut
through the peg.

26. Another
simple method of controlling expansion and creating a ledge for the cone to
sit on is to wrap fiberglass reinforced packing tape around the top of the
bottle until it has created a ledge.

27. Practice
many times in all conditions including rain.

28. Have a
written procedure and follow it every time. The teams I coach follow step by
step through their checklist every time even though they know it by heart.
Airline pilots and surgeons both use checklists, shouldn't you? Laminate
your checklist!

29. How heavy
should my rocket be? That is a good question. The weight that would give
the rocket the best loft may not allow it to reach the highest altitude. Go
for stability first, loft second, altitude third. Try to reach a good
compromise.

30. How much air
pressure do I use? Easy question, all that is allowed. The more stored
energy, the higher you go.

31. Use this
flight simulator to determine the best amount of water.
http://homes.managesoft.com.au/~cjh/rockets/simulation/

32. Check the
opening of your bottle, a standard piece of 1/2 inch, Schedule 40 PVC pipe
through the nozzle of your rocket. If it will pass through the opening, it
will launch from any standard launcher.

33. With rocket
designs where a tall cone sits loosely on the bottle, the cone mass can do
little to correct an initial flight stability issue. Why? Because when the
fins attempt to correct the instability, the rocket can bend in the middle
where the cone sits on the bottle. If you notice that you are getting a lot
of pre-deployments, you may attempt to move some of your cone mass toward
the base of the cone or you may choose to shorten your cone.

34. Make sure
that you have a waterproof box to store your rocket and supplies. Also make
sure you have an umbrella to cover the rocket while staging and before
launch. Bring rain gear for yourself. The last 2 years at nationals we have
had intense rain and many rockets were damaged.

35. Try not to
use paper, cardboard or wood components in the rocket. If you do, attempt to
waterproof them.

36. Bring too
much clothing. You don't have to wear it, may want to. When cold or wet it
is hard to concentrate.

37. Know the
launcher that will be used at the event you are going to attend. This is a
particular concern for rockets that have fins that are swept below the
flange on the bottleneck. Many launchers including the typical "Bent Fork
Launchers" and the NERDS launcher will not launch rockets with swept fins.
If you plan to use a swept fin rocket, I recommend that you contact the
event supervisor or event director to determine what type of launcher will
be used. In the past at nationals a launcher that is capable of launching
all typical rocket fin configurations has been used, but it still doesn't
hurt to check.

38. I recommend
a fin jig be used for installing fins with precision. A fin jig is a
necessity when using slow set glues. You can see my fin jig at my rocket web
site: http://txsnapper.eezway.org/powerdeployment

39. To measure
your water, build you own custom measuring device from a 1 Liter Bottle.
Mark it for just the right amount of water for your rocket. This will help
eliminate measuring mistakes.

40. Mark your
rocket with the correct water level as a double check.

41. If you are
going to be launching off a launcher where you will have to tip your rocket,
rather than the launcher tipping for loading, always put in a little too
much water. As you tip your rocket you will always lose a little water. You
can lift up on your rocket gently to let out a little water while on the
pad. (Don't get too bent out of shape if you don't have exactly the correct
amount of water, a few ml of water will not make that much difference)